This invention relates to a method of and apparatus for advancing a plurality of longitudinally arranged pre-fabricated constructional units for construction of an underground structure of a form adapted for a special purpose such as tunnel excavation (including galleries, passages and wells), heavy load transportation, underwater tunnel installation, or muddy water dredging excavation forwardly successively from the forwardmost through the intermediate to the tailing constructional unit relative to the others and relative to the ground in a self-running manner.
Of the above mentioned purposes, the heavy load transportation, for example, has been practiced in the prior art at an increased high speed while sacrificing the safety operation with the result of frequent occurrence of serious accidents, as the maintenance of safety operation leads to economic disadvantages due to the decrease in the transportation efficiency. In other words, increasing transportation speeds are ultimately to be realized by employment of high power driving machines which increase the probability of occurrence of large-scale terrible accidents.
In driving a tunnel (including underground excavations such as galleries, passages and wells), it has been the prior art practice to employ machines for picking and hauling away the spoil to disposal at a high efficiency. Each time an explosive charge is shot, however, a large amount of spoil-fly is generated and the working area must be cleared of operators and equipments thereby the effectiveness of employment of the machines is diminished. The extension of the railway for the working tractors requires so much labor and time, and moreover, it is difficult to lay the rail near to the spoil-picking place, thereby the total run of excavation is caused to associate with various drawbacks and the desired continuous and time saving operation can not be performed so that such a prior art method is rendered uneconomical. In order to eliminate the above mentioned problems, the provision of working platforms has so far been made to clear the area of the operators with the result that the effectiveness of employment of the machines is increased. The necessary facilities require an added large expense which is an avoidable disadvantage of the prior art.
As a method of excavating a gallery according to the prior art, it is known to operate a plurality of constructional units in such a manner that two constructional units are selected as separated apart from each other and opposedly disposed to each other, then one of the two units is advanced toward the other by use of a mechanism comprising a traction jack, a traction member and anchoring members, these parts being arranged to create a reaction force at the selected one of the two constructional units which can be utilized to advance the other constructional unit relative to the ground, then after the latter constructional unit has been advanced, the former one is advanced by utilizing the reaction force created at the latter by the mechanism. With this arrangement, however, the traction force of the traction jack, because of its application only to the individual constructional units, is limited in effect. Moreover, the traction force is rendered effective when the reaction force of the opposite side constructional unit is utilized as the reaction force therefor, so that each time the advancing operation is transferred from one to another constructional unit, the reaction force must be renewed between the successively paired constructional units. The expense to creating this new reaction force amounts up to a very large level.
For installation of an underwater tunnel at a desired site, according to the prior art, a foundation on which the tunnel structure is to be installed is prepared in a flat form or in a grooved form, then the entire tunnel structure is divided into a suitable number of constructional units which are prefabricated on the land, then these constructional units are transported one by one on water by ships or by towing under the self-buoyant action to a location just above the site of installation, then they are sunk into the bottom of the water body at which the individual constructional units are jointed with each other to construct the installation of a single tunnel structure.
Such a prior art sunk-installation method, however, is very much susceptible to weather conditions and is associated with a considerably low rate of operation per year. Another disadvantage is that the transportation of the individual constructional units on land and on water, and the sinking operations thereof require large-scale various equipments and a large amount of expense therefor. In addition thereto, it is necessary to take into account the passage of ships having no relation to the transportation of the constructional units and travelling near the spot. Further, it is very difficult to sink the individual constructional units accurately from the water surface to the installation site on the bottom of the water body.
In the case of the construction of an underground structure in a water pressure-acting ground, according to the prior art using a compressed air in preventing seepage flow of water and cave-in of the ground, the compressed air producing equipment is positioned outside the underground structure, namely on the land, as separated from the air pressure buffering chamber by a large distance. As the excavation proceeds, therefore, the air pressure buffering chamber advances forwardly, while leaving the compressed air producing equipment stationary behind, thereby the distance therebetween is increased which in turn calls for an increase in the length of the interconnection pipe means between the air pressure buffering chamber and the compressed air producing equipment. This requires complicated operations and large labor and time with a large amount of expense. Furthermore, the installation of the compressed air producing equipment chamber requires a large area of the ground, thereby giving an additional disadvantage of increasing the cost of production of the underground structure installation due to the difficult negotiation for securing the site, the additional expense therefor, and a considerably elongated period of the preparatory and installation operation. Further, when the installation site of the compressed air production chamber is located near a populated area, some elaborate and expensive precautions must be made or otherwise the extensive noise would give rise to complaints. For example, the provision for shielding the noise of the compressed air producing chamber, or of an underground room for accommodation of it. Furthermore, as the interconnection pipe lines for transporting the compressed air are increased in length, their installation, operation and maintenance are very disadvantageous from the economical, operation efficiency and safety standpoints.
In the case of the construction of an underground structure in a relatively soft sandy ground, according to the prior art, a water jet is applied to the excavating surface of the tunnel, and the spoil is converted to a muddy water body which is pumped out onto the land, and the settling operation is performed by use of various means, thus excavating operation is carried out while the muddy water body being separated into water and soil.
Such a prior art excavating method has various disadvantages, one of which is that the transportation of a large amount of muddy water from the excavating spot to the land through a number of pipes of long length causes frequent occurrence of blockages in the pipes by the solidified muddy water body passing therethrough and another disadvantage which is that a large number of settling vessels of large volume are necessary which in turn calls for a large area for the site of its installation. Another disadvantage is that the amount of material of the pipes weared out by the passage of the muddy water therethrough is very large which leads to an increase of the percentage of damaged pipes Still another disadvantage is that when the current of the muddy water is stopped in order to interchange the damaged pipe by a new one, or to extend the pipe line by addition of new pipes, the frequency of occurrence of pipe blockages is increased because the soil particles in the muddy water body is liable to deposit.
The water necessary for converting the spoil into a muddy water body is transported from the land to the excavating spot, and further in general the muddy water chamber and various equipments necessary for the excavation are provided as separated from the underground structure body but as arranged outside thereof as a temporary structure body. This temporary structure body must be constructed in so rigid a form that it can withstand against the very strong pressure of water and this requires a very large expense. After the construction of the underground structure has been completed, this temporary structure body must be removed and transported onto the land, and this also requires a very large amount of expense.
In driving a tunnel, a plurality of constructional units for construction of an underground structure are arranged along a common longitudinal line, and all the individual constructional units are interconnected by a common linking member and advanced individually subsequently from the forwardmost to the tailing constructional unit relative to the others and relative to the tunnel ground in a self-running manner while utilizing as a reaction force the sum of the frictional forces of the other stationary constructional units against the part of the tunnel wall which is usually the bottom of the tunnel wall when the tunnel is excavated in a hard ground. These frictional forces have at random magnitudes so that so far as the reaction force is derived from only these frictional forces, the forwrd advancement of the constructional units relative to the tunnel ground is made different in one step distance from one unit to another, or almost impossible.
Further taking into account the resistance force necessary to locate the forwardmost constructional unit with a cutter at the front thereof in position for excavating the hard rock of the front face of the tunnel, and to haul away the spoil accumulated in front of or in rear of the cutter, it is impossible to achieve the perfect forward advvancement of the individual constructional units inasmuch as only the uncertain frictional resistances of the bottom walls of the ones of the constructional units which remain stationary during the advancement of the selected one constructional unit and at random small frictional resistances of the upper and side walls thereof are utilized as the reaction force for the advancement of the selected one constructional unit.